WO2014033321A1

WO2014033321A1 - Process for preparing aromatic polyethersulphones

Info

Publication number: WO2014033321A1
Application number: PCT/EP2013/068187
Authority: WO
Inventors: Faissal-Ali El-Toufaili; Achim Stammer; Simon Gramlich; Angela ULZHÖFER
Original assignee: Basf Se
Priority date: 2012-09-03
Filing date: 2013-09-03
Publication date: 2014-03-06
Also published as: KR20150052224A; EP2892943B1; JP2019143159A; KR102161036B1; EP2892943A1; CN104769014A; CN109880099A; JP2015526579A; JP6775632B2

Abstract

The process for preparing aromatic polyethersulphones by reaction of a dichlorodiphenyl sulphone component with a bisphenol component as monomers, in the presence of alkali metal carbonate, in the melt, in the absence of solvents or diluents, is characterized in that the reaction is carried out in a mixing kneader which is operated with a shear rate in the range from 5 to 500 s^-1.

Description

The invention relates to a process for the preparation of aromatic polyethersulfones and to the polyethersulfones obtainable in the process.

Aromatic polyethersulfones are usually prepared by condensing a dichlorodiphenylsulfone component with a bisphenol component as monomers in the presence of alkali metal carbonates. Usually, the polycondensation is carried out in a solvent such as N-methylpyrrolidone (NMP). Such a method has the disadvantage that a toxic solvent must be handled, which must be separated from the product after the reaction, optionally purified and recycled to the reaction. DE-A-27 49 645 relates to a process for preparing polyethers in which substantially equivalent amounts of a bisphenol and a dihalobenzene compound are condensed in the absence of solvents or diluents and in the presence of anhydrous alkali carbonate. As devices, the usual for polymers kneaders or extruders, which have a device for removing volatile components, called. In the examples, the device used is not further characterized.

The object of the present invention is to provide a process for the preparation of aromatic polyethersulfones by reacting a dichlorodiphenylsulfone component with a bisphenol component as monomers in the presence of alkali metal carbonate in the melt in the absence of solvents or diluents, high molecular weights to be accessible and the aromatic polyethersulfones should discolour as little as possible.

The object is achieved according to the invention by a process for the preparation of aromatic polyethersulfones by reacting a dichlorodiphenylsulfone component with a bisphenol component as monomers in the presence of alkali metal carbonate in the melt in the absence of solvents or diluents, the reaction being carried out in a mixer. ter operated with a shear rate in the range of 5 to 500 s ^_1 . The degree of filling of the mixing kneader according to the invention is preferably in the range from 0.2 to 0.8, preferably 0.22 to 0.7, in particular 0.3 to 0.7, especially 0.35 to 0.64.

The term "degree of filling" indicates what proportion of the free volume in the kneader, which can be filled with monomers and permits thorough mixing, is filled by the starting monomers, thus indicating a degree of filling in the range from 0.2 to 0.8 that 20 to 80% of the Filling with monomers and their mixing available free volume in the process of filling with monomers and alkali carbonate can be used.

The shear rate is defined as the gradient of the velocity in the kneaded material in the gap between the rotating kneading bar and the wall, s = 2 n * TT ^* d _ra t / (di-d _ra t) with the speed n [s ^_ ¹ ], the rotor diameter d _ra t [m] and the inner diameter of the apparatus d, [m]. It describes the extent of shear through the mixing elements in the kneader, typically the shear between the rotor and outer wall, or between ingot and stator. The shear rate is in the range of 5 to 500 s ^-1 , preferably 10 to 250 s ^-1 , in particular 20 to 100 s ^-1 .

Is a s-value of s / 2 is used, the shear rate is in the range of 5 to 500 s ^_1, preferably 25 to 100 S ^"1, in particular 35 to 70 s ^_1.

As a mixing kneader, all known suitable mixing kneaders can be used, which allow heating to above the melting point of the monomers and allow the discharge of gaseous condensation products. Suitable mixing kneaders usually have one or preferably at least two axially parallel rotating shafts, of which the main shaft can have disc surfaces with kneading bars arranged on their circumference. Suitable mixing kneaders are, for example, in

DE-A-41 18 884 and DE-A-199 40 521. Preferably, the mixing kneader has a rotor which is operated at a speed in the range of 5 to 50 revolutions per minute, particularly preferably 7.5 to 40 revolutions per minute and in particular 10 to 30 revolutions per minute.

The mixing kneader used according to the invention has the advantage that the residence time can be substantially longer than in the extruder. In addition, the degassing is much easier and more widely possible, so that the gaseous polycondensation products can be discharged in a simple manner. In addition, the inventive shear rate can be adjusted more easily in the mixing kneader. The process according to the invention can be carried out as a batch process or as a continuous process. Preferably, the process is carried out continuously, wherein preferably continuously operated biaxial mixing kneaders are used, as they are available for example as LIST TCF or BUSS SMS. The combination of mixing kneader, degree of filling and shear rate makes it possible according to the invention to achieve high molecular weights of the aromatic polyethersulfones without the product suffering from discoloration. In the process according to the invention, a large number of different aromatic polyethersulfones can be prepared in which one or more dichlorodiphenylsulfone components are reacted with one or more bisphenol components as monomers.

The aromatic groups of the polyethersulfones, also referred to as arylene groups, may be the same or different and independently of one another represent an aromatic radical having 6 to 18 carbon atoms.

Examples of suitable arylene groups are phenylene, bisphenylene, terphenylene, 1, 5-naphthylene, 1, 6-naphthylene, 1, 5-anthrylene, 9,10-anthrylene or 2,6-anthrylene. Of these, preferred are 1,4-phenylene and 4,4'-biphenylene. Preferably, these aromatic radicals are not substituted. However, they can carry one or more substituents. Suitable substituents are, for example, alkyl, arylalkyl, aryl, nitro, cyano or alkoxy groups and heteroaromatics such as pyridine and halogen atoms. The preferred substituents include alkyl radicals having up to 10 carbon atoms such as methyl, ethyl, i-propyl, n-hexyl, i-hexyl, Ci to Cio alkoxy such as methoxy, ethoxy, n-propoxy, n-butoxy, aryl radicals with up to 20 carbon atoms, such as phenyl or naphthyl, as well as fluorine and chlorine. Furthermore, preference is given to substituents obtained by reaction of the polyarylene ether sulfones with a reactive compound which, in addition to a C-C double or triple bond, contains one or more carbonyl, carboxylic acid, carboxylate, acid anhydride, acid amide, acid imide, carboxylic acid ester, amino , Hydroxyl, epoxy, oxazoline, urethane, urea, lactam or halobenzyl groups. The arylene groups of the polyarylene ethers besides -SO 2 -, z. B. -O-, -S-, - SO-, -CO-, -N = N-, -COO-, an alkylene radical, which may be substituted if desired, or a chemical bond to each other.

Polyarylene ether sulfones which can be used according to the invention can be synthesized from recurring units of the formula I.

wherein

t and q are independently 0, 1, 2 or 3,

Q, T, and Z are each independently a chemical bond or a group selected from -O-, -S-, -SO2-, S = O, C = O, -N = N-, -R ^a C = CR ^b - and -CR ^c R ^d -, where

R ^a and R ^b are each independently a hydrogen atom or a C 1 -C 12 alkyl group, and R ^c and R ^d independently of one another each represent a hydrogen atom or a C 1 -C 12 -alkyl-,

Ci2-alkoxy or C6-Ci8-aryl group stand,

in which

R ^c and R ^{d are} optionally substituted independently of one another by fluorine and / or chlorine atoms or, if appropriate together with the carbon atom to which they are attached, form a C 3 -C 12 -cycloalkyl group which is optionally substituted by one or more carbon atoms C6 alkyl groups, provided that at least one of the groups T, Q and Z is -SO2- and, when t and q are 0, Z is -SO2-,

Ar and Ar ¹ independently of one another are C 6 -C 18 -arylene groups, these being optionally substituted by C 1 -C 12 -alkyl, C 6 -C 18 -aryl, C 1 -C 12 -alkoxy groups or halogen atoms.

The aromatic polyethersulfones preferably have at least one of the following structural units:

The dichlorodiphenylsulfone components and bisphenol components used as monomers are derived from these structures. For example, dichlorodiphenylsulfone and dihydroxydiphenylsulfone are used for the preparation of polyethersulfones. Such products are available, for example under the name Ultrason ^® E from BASF SE.

The reaction of dichlorodiphenyl sulfone and 4,4'-biphenol leads to polyphenylene, which is available from BASF SE as Ultrason ^® P.

Further suitable monomers are described, for example, in DE-A-27 49 645, WO 01/83618 and WO 2010/146052. In the reaction, equimolar amounts of dichlorodiphenylsulfone component and bisphenol component can be used, or one of the components, typically the more volatile, can be used in excess.

If the mixing kneader is equipped with a reflux condenser to condense evaporating monomers and the condensed monomers are returned to the mixing kneader, it is possible to work with equimolar amounts of the two monomer components, or with slight deviations therefrom.

The process according to the invention can be carried out at any suitable temperatures, provided that the monomers are present in the melt. Preferably, the reaction is carried out at a temperature in the range of 250 to 350 ° C.

In the mixing kneader, the reaction is preferably carried out without pressure, wherein in the polycondensation resulting low molecular weight condensation products are discharged in gaseous form.

In the reaction, the alkali metal carbonate, which is preferably potassium carbonate, can be introduced as a separate component in the mixing kneader. However, it can also be used premixed with at least one of the monomers. In the condensation of bisphenols with Dihalogenbenzolverbindungen first bisphenol and alkali metal carbonate can be reacted, the product is then polycondensed in the mixing kneader with the Dihalogenbenzolverbindung. It is also possible to mix it into the dihalobenzene compound.

In a continuously operated mixing kneader different feed systems for the monomers and alkali carbonate can be used. It can handle a liquid dosage be used, wherein molten monomers are metered. Preferably, as described, the alkali carbonate is predispersed in at least one of the monomer components, preferably in the halogen-containing monomer due to its reactivity with the phenolic groups and the formation of salts.

The metered addition can also be carried out in solid form by gravimetric dosing or by a lateral entry screw. When entering through the hood of the mixing kneader, it must be ensured that there is no blockage by solids. A minimum diameter of the hood of 150 mm is advantageous, as well as a short discharge path of the solid powder perpendicular to the kneading bars. The monomers can also be granulated to adjust their flow behavior. When using a side entry screw, the monomers and alkali carbonate in powder form must be introduced into the side entry screw and introduced through it into the mixing kneader. The degree of filling in the mixing kneader can be controlled by the operation of a discharge screw, which removes product according to the entry in the mixing kneader.

The reaction time in the mixing kneader can be freely selected depending on the desired molecular weight of the aromatic polyethersulfone. The reaction time in the mixing kneader is preferably from 1 to 3.5 hours, particularly preferably from 1.5 to 3 hours.

If work is carried out without a reflux condenser, the amount of dichlorodiphenyl sulfone should typically be increased by about 4 to 6 mol%, since this compound evaporates more readily than the dihydroxydiphenylsulfone component because of its vapor pressure of about 100 mbar at a temperature of 300 ° C.

The invention also relates to aromatic polyethersulfones obtainable by the process described above. Such aromatic polyethersulfones preferably have a number average molecular weight of above 10,000, with the number average molecular weight preferably ranging from 10,000 to 26,000. The polydispersity is preferably 2 to 7.5, particularly preferably 2.4 to 3.2 for biphenol-based products, and more preferably 3 to 7.5 for DHDPS-based products.

The invention is further illustrated by the following examples.

Examples

General procedure Polyethersulfone (PESU) is prepared by reacting dichlorodiphenylsulfone (DCDPS) with dihydroxydiphenylsulfone (DHDPS) in the presence of potassium carbonate as base. As condensation byproducts fall potassium chloride as a particulate salt, water and Carbon dioxide. Due to the melting point of DHDPS of 247 ° C, the reaction is typically carried out at a temperature of about 300 ° C.

Similarly, the reaction of dichlorodiphenyl sulfone (DCDPS) with 4,4'-biphenol (BPhOH) to polyphenylene sulfone (PPSU). The reaction takes place in a mixing kneader LIST DTB, a Einschachtmischkneter with self-cleaning system of kneading bars and hooks. In the laboratory experiment, the void volume of the mixing kneader was about 770 ml.

The mixing kneader is heated by means of a thermostat, whereby only heating of the outer wall is possible. The three starting substances are introduced into the reactor as solid powders. After purging with argon, the reactor is heated to the reaction temperature, kept for the required reaction time at this temperature and then cooled.

During the reaction, the motor of the mixing kneader typically moves with one

Speed of about 20 revolutions per minute. Upon cooling, the temperature in the reactor falls below the glass transition temperature of the polymer and the rotor must be shut off. After this

Cooling, the polymer was removed mechanically. The reactor is operated at ambient pressure.

During the reaction, the condensation products of water and carbon dioxide are distilled off and discharged from the reactor with an excess argon flow of 10 l / h. Unless a reflux condenser is used, the monomer DCDPS is partly carried away due to its high vapor pressure. In order to obtain high molecular weights, an excess of about 4 mol% of DCDPS must be used, unless a reflux condenser is used.

In all experiments, the molar ratio of potassium carbonate to DHDPS is set to 1:06. Example 1 Table 1 shows the experimental conditions and results for the preparation of polyethersulfone. The batch cycle time t _c is given in addition to reaction temperature, rotor speed, monomer amounts and molar ratio.

After the reaction, the product was mechanically discharged from the mixing kneader, ground to a particle size of about 2 mm and washed twice with water for three hours at 80 ° C. This allowed about 80% by weight of the by-produced potassium chloride to be removed. Due to the residual content of potassium chloride, the certain viscosity number VN is lower compared to a pure polymer. The molecular weights were determined by GPC methods. Table 1

The degree of filling of the mixing kneader was 0.22 in these examples. The rotation speed of 20 revolutions per minute corresponds to a shear rate of 100 s ^_1 .

It can be seen from the results of Table 1 that the viscosity number increases with increasing temperature, as well as with increasing residence time. The more the molar ratio deviates from the stoichiometry, the lower the viscosity number.

The speed of rotation of the mixer was varied in Comparative Experiments V50 and V51, with both rotor standstill and high rotational speed resulting in molecular weight reduction. Without sufficient rotation, the formation of new interfaces between gas phase and melt is absent, so that the condensation products of water and carbon dioxide can not be sufficiently dissipated. If the rotational speed was too high, the shear stress of the melt was increased by a factor of ten. The color of the product was much darker compared to Example 5. In addition, gel particle formation occurred.

Example 2

In a further experiment, the degree of filling of the mixing kneader was changed. Since the molar ratio of potassium carbonate was reduced with respect to DHDPS, a somewhat reduced VN was also observed. The results are shown in Table 2 below. Table 2

The stirring speed of 20 revolutions per minute again corresponds to a shear rate of 100 s- ¹ .

The results show that significantly reduced molecular weights are obtained for too high and too low fill levels.

Example 3

Analogous experiments were carried out for the reaction of DCDPS with 4,4'-biphenol. The results are summarized in Table 3 below.

Table 3

Experiment No. 12 13 14 15 16 17 18 19

DCDPS (A) [g] 140.46 139.72 141, 18 140.46 140.46 140.46 140.46 140.46

Biphenol (B) [g] 89.29 89.71 88.89 89.29 89.29 89.29 89.29 89.29

K2C03 [g] 70.25 70.58 69.93 70.25 70.25 70.25 70.25 70.25

Molar ratio A / B 1, 02 1, 01 1, 03 1, 02 1, 02 1, 02 1, 02 1, 02

Tr [° C] 300 300 300 300 300 310 290 300/310 tc [hr] 3 3 3 2 4 3 3 0,5 / 2,5

VN [ml / g] 55.6 61, 1 44.1 56.1 36.6 60.3 35.9 62.2

Mn [g / mol] 16,400 26,000 15,800 19,300 1 1,000 22,200 12,300 21,600

Mw [g / mol] 50.300 63.600 39.000 51.200 29.500 62.600 30.800 63.000

Mw / Mn 3.1 2.5 2.5 2.7 2.7 2.8 2.5 2.9 The procedure and workup were as in the experiments of Table 1. The stirrer speed was 20 revolutions per minute, the shear rate 100 s ^_1 , the fill level 0.22. It was also observed that the viscosity number dropped with extended reaction time. Too long a residence time seems to lead to a decomposition. Therefore, the reaction time in the mixing kneader is preferably at most three hours.

Example 4

To allow a comparison between the use of a mixing kneader and an extruder, a two-screw kneader (LIST TCP) with a free volume of 3.2 l and a reflux system for the monomers was used. Potassium carbonate was used in excess of 6 mol%. The stirrer speed was 20 revolutions per minute, the degree of filling was 0.22, the shear rate 30 s ^_1 . For the comparative experiment, a laboratory extruder was used for the polycondensation. Since the extruder does not allow reaction times of more than 30 minutes, the reaction time was set evenly to 30 minutes in this experiment. The results are summarized in Table 4 below.

Table 4

As can be seen from the results, the use of the mixing kneader leads to a much higher molecular weight. The product thus obtained also has a markedly lighter intrinsic color, while the product from the extruder was colored brown. This makes it clear that the use according to the invention of a mixing kneader is advantageous. Example 5

The monomers DCDPS, DHDPS and K ₂ C0 ₃ are premixed in the apparatus shown schematically in Fig. 1 in the molar compositions shown in Table 5 and in the solid feed of the gravimetric feeder. By means of gravimetric dosing, the feedstocks are continuously fed into the screw feeder (feeder screw) according to the set throughput and from there into the kneader. The stuffing screw is cooled, so that the starting materials are still in solid form. In the kneader, the feedstocks DCDPS and DHDPS are melted and begin to react with the potash. This forms the polymer and the by-products H ₂ 0, C0 ₂ and KCl. The gaseous components H ₂ 0 and C0 ₂ are degassed (off gases) and leave the reaction chamber via the exhaust pipe. Part of the monomer DCDPS sublimates into the gas phase and is carried along with it and is condensed out of a condensing condenser and returns to the process space.

The feeds are mixed by the rotating kneader and polymerize while being transported in the axial direction through the kneader. At the outlet of the kneader there is a discharge screw, which discharges the present polymer melt (product), which still contains KCl, out of the mixing kneader. Optionally, behind the discharge screw a melt pump can be switched, with which the discharged amount can be dosed, and a string or underwater granulation can be connected. The speeds (in min ^"1 ) correspond to the following shear rates (in s ^{" 1} )

5 - 7,4

15 - 22.2

30 - 44.2

50 - 74

Table 5

Product

Claims

claims

1 . Process for the preparation of aromatic polyethersulfones by reacting a dichlorodiphenylsulfone component with a bisphenol component as monomers in the presence of alkali metal carbonate in the absence of solvents or diluents, characterized in that the reaction is carried out in a mixing kneader having a shear rate in the range of 5 to 500 s ^{_1 is} operated.

2. The method according to claim 1, characterized in that the degree of filling of the mixer in the range of 0.2 to 0.8, preferably 0.22 to 0.7, is located.

3. The method according to claim 1 or 2, characterized in that the shear rate of the mixing kneader is in the range of 10 to 250 s ^_1 .

4. The method according to any one of claims 1 to 3, characterized in that the mixing kneader has a rotor which is operated at a speed in the range of 5 to 50 revolutions per minute.

5. The method according to any one of claims 1 to 4, characterized in that the alkali carbonate is anhydrous.

6. The method according to any one of claims 1 to 5, characterized in that the mixing kneader is equipped with a reflux condenser for condensing evaporating monomers and the condensed monomers are recycled to the mixing kneader.

7. The method according to any one of claims 1 to 6, characterized in that it is carried out at a temperature in the range of 250 to 350 ° C.

8. The method according to any one of claims 1 to 7, characterized in that it is carried out continuously.

9. The method according to any one of claims 1 to 8, characterized in that the alkali metal carbonate is used premixed with at least one of the monomers.

10. The method according to any one of claims 1 to 9, characterized in that the aromatic polyethersulphones have at least one of the following structural units:

17

Aromatic polyethersulfone obtainable by the process according to any one of claims 1 to 10.